I went to the post office to mail 2 small 'packages'.
Envelope #1 contained one 6 1/2" block and the 7" x 8 1/2" envelope was flat.
Envelope #2 contained a few FQ and some other small fabrics and the envelope was 'thick'.
I could mail #2 as first class and apply delivery confirmation.
I could not mail #1 as first class and get delivery confirmation - *because it wasn't thick enough*. I had to step up to Priority for $4.95 and then I could get delivery confirmation. I was told that people actually put cardboard or something in these flat envelopes to make them thicker so that they could be mailed 1st class.
This does NOT make sense - why are things so complicated.